The Queue Interface

The Queue interface in Java is part of the Java Collection Framework and is used to store a collection of elements. It extends the Collection interface and is designed to hold elements prior to processing. The Queue interface is a subtype of the java.util package and defines a few methods that can be used to manipulate the elements of the queue.

The Queue interface is typically implemented using a First-In-First-Out (FIFO) approach, where the first element added to the queue is the first element to be removed. It can also be implemented using a Last-In-First-Out (LIFO) approach, where the last element added to the queue is the first element to be removed.

Some of the methods provided by the Queue interface include:

add(element): Adds an element to the queue and returns true if the operation was successful.

offer(element): Adds an element to the queue and returns true if the operation was successful.

remove(): Removes the head element of the queue and returns it. Throws an exception if the queue is empty.

poll(): Removes the head element of the queue and returns it. Returns null if the queue is empty.

element(): Returns the head element of the queue without removing it. Throws an exception if the queue is empty.

peek(): Returns the head element of the queue without removing it. Returns null if the queue is empty.

Some of the classes that implement the Queue interface include:

LinkedList: A linked list implementation of the Queue interface.

PriorityQueue: An unbounded priority queue implementation of the Queue interface.

ArrayDeque: An unbounded double-ended queue implementation of the Queue interface. The Queue interface is useful in a wide variety of applications, including data processing, task scheduling, and message passing systems.